Multiple resonator dielectric filter

• US 4,829,274 A
• Filed: 09/03/1987
• Issued: 05/09/1989
• Est. Priority Date: 07/25/1986
• Status: Expired due to Term

• Current Assignee: CTS Corporation
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Green, Steven R., Sokola, Raymond L., De Muro, David M.
• Primary Examiner(s): Nussbaum, Marvin L.
• Application Number:
  US07/092,870
• Time in Patent Office: 614 Days
• Field of Search: 333/202, 333/204-207, 333/219, 333/222, 333/223, 333/245, 333/246, 455/73, 455/78-83, 370/30, 370/36, 370/38
• US Class Current: 333/202
• CPC Class Codes: H01P 1/2056 Comb filters or interdigital filters with metallised resonator holes in a dielectric block
• CPC Class Codes: H01P 1/2136 using comb or interdigital filters; using cascaded coaxial cavities H01P1/2131, H01P1/2135 take precedence

Abstract

A multiresonator dielectric block filter is disclosed in which capacitive coupling between resonators disposed in the dielectric block is controlled by an electrode strip coupled to the conductive material covering the majority of the dielectric block surface. The electrode strip extends at least partially between two adjacent resonators to control the capacitive coupling between the resonators.

Claims

1. A dielectric filter for passing a band of radio frequencies and rejecting other bands of frequencies, comprising:

a volume of dielectric material having first, second, and side surfaces, said second and side surfaces being substantially covered with a conductive material;

a plurality of holes extending through said dielectric material from said first surface to said second surface, the surface of at least two of said holes being substantially covered with a conductive material which is electrically common at said second surface, thereby forming at least two resonators; and

electrode means disposed on said first surface, connected to said conductive material of said side surface, and extending partially between a first surface hole of a first resonator of said at least two resonators and a first surface hole of a second resonator of said at least two resonators, whereby coupling between said first resonator and said second resonator may be limited.

2. A dielectric filter in accordance with claim 1 wherein said electrode further comprises two strips of conductive material disposed essentially perpendicular to a line drawn between said first surface hole of said first resonator and said first surface hole of said second resonator, said two conductive strips having a first end and a second end, a gap between said first end of each said conductive strip, and said second end of each said conductive strip connected to said conductive material of said side surface.

3. A dielectric block filter for passing a band of radio frequencies from an input to an output, comprising:

a rectangular prismatic dielectric block having first, second, and side surfaces, said second and side surfaces being substantially covered with conductive material;

a plurality of holes extending through said rectangular prismatic dielectric block from said first surface to said second surface, the surface of at least some of said holes being substantially covered with a conductive material which is electrically common at said second surface, thereby forming resonators from said at least some holes;

input coupling means coupled to a first resonator;

output coupling means coupled to a second resonator; and

electrode means disposed on said first surface, connected to said conductive material of said side surface, and extending partially between the first surface hole of said first resonator and a first surface hole of a third resonator, whereby coupling between said first resonator and said third resonator may be limited.

4. A dielectric block filter in accordance with claim 3 further comprising tuning means coupled at least at said first surface to each said resonator, whereby each resonator may be adjusted for frequency of resonance.

5. A dielectric block filter in accordance with claim 3 further comprising a fourth resonator coupled to said input coupling means and adjusted to provide a transmission zero outside of the pass band of radio frequencies.

6. A dielectric block filter in accordance with claim 3 wherein said electrode means further comprises two strips of conductive material disposed essentially perpendicular to a line drawn between said first surface hole of said first resonator and said first surface hole of said third resonator, said two conductive strips having a first end and a second end, a gap between said first end of each said conductive strip, and said second end of each said conductive strip connected to said conductive material of said side surface.

7. A dielectric block filter for passing a band of radio frequencies from an input to an output, comprising:

a rectangular prismatic dielectric block having first, second, and side surfaces, said second and side surfaces being substantially covered with a conductive material;

a plurality of holes extending through said rectangular prismatic dielectric block from said first surface to said second surface, the surface of at least some of said holes being substantially covered with a conductive material which is electrically common at said second surface, thereby forming resonators from said at least some holes;

input coupling means coupled to a first resonator;

output coupling means coupled to a second resonator; and

electrode means disposed on said first surface, connected to said conductive material of said side surface, and extending partially between the first surface hole of said second resonator and a first surface hole of a third resonator, whereby coupling between said second resonator and said third resonator may be limited.

8. A dielectric block filter in accordance with claim 7 further comprising tuning means coupled at least at said first surface to each said resonator, whereby each resonator may be adjusted for frequency of resonance.

9. A dielectric block filter in accordance with claim 7 further comprising a fourth resonator coupled to said output coupling means and adjusted to provide a transmission zero outside of the pass band of radio frequencies.

10. A dielectric block filter in accordance with claim 7 wherein said electrode means further comprises two strips of conductive material disposed essentially perpendicular to a line drawn between said first surface hole of said second resonator and said first surface hole of said third resonator, said two conductive strips having a first end and a second end, a gap between said first end of each said conductive strip, and said second end of each said conductive strip connected to said conductive material of said side surface.

11. A multi-passband dielectric filter for coupling radio-frequency (RF) signals between an antenna and first and second RF signal utilization means, comprising:

at least two volumes of dielectric material, each volume of dielectric material having first, second, and side surfaces, said second and side surfaces of each volume of dielectric material being substantially covered with a conductive material;

a plurality of holes extending through each said volume of dielectric material from said first surface to said second surface, the surface of at least two of said holes through each of said volume o;

dielectric material being substantially covered with a conductive material which is electrically common at said second surface of each respective volume of dielectric material, thereby forming at least two resonators in each said volume of dielectric material;

electrode means disposed on said first surface of at least one of said volumes of dielectric material, connected to said conductive material of said side surface, and extending partially between a first surface hole of a first resonator of said at least two resonators and a first surface hole of a second resonator of said at least two resonators, whereby coupling between said first resonator and said second resonator may be limited; and

coupling means for coupling a first volume of dielectric material having said at least two resonators therein tuned to a first passband of frequencies and a second volume of dielectric material having said at least two resonators therein tuned to a second passband of frequencies to a single node at the antenna, whereby said first passband of frequencies is passed by said first volume of dielectric material and said second passband of frequencies is rejected by said first volume of dielectric material and said second passband of frequencies is passed by said second volume of dielectric material and said first passband of frequencies is rejected by said second volume of dielectric material.

12. A multi-passband filter in accordance with claim 11 wherein said electrode means further comprises two strips of conductive material disposed essentially perpendicular to a line drawn between said first surface hole of said first resonator and said first surface hole of said second resonator, said two conductive strips having a first end and a second end, a gap between said first end of each said conductive strip, and said second end of each said conductive strip connected to said conductive material of said side surface.

13. A multi-passband filter in accordance with claim 11 further comprising a third resonator in at least one of said volumes of dielectric material, said third resonator adjusted to provide a transmission zero outside of said passband of said at least one of said volumes of dielectric material.

14. A radio utilizing an antenna to receive radio frequency signals, comprising:

a receiver; and

a filter disposed between said receiver and the antenna, said filter comprising;

a volume of dielectric material having first, second, and side surfaces, said second and side surfaces being substantially covered with a conductive material;

a plurality of holes extending through said dielectric material from said first surface to said second surface, the surface of at least two of said holes being substantially covered with a conductive material which is electrically common at said second surface, thereby forming at least two resonators; and

electrode means disposed on said first surface, connected to said conductive material of said side surface, and extending partially between a first surface hole of a first resonator of said at least two resonators and a first surface hole of a second resonator of said at least two resonators, whereby a coupling between said first resonator and said second resonator may be limited.

15. A radio in accordance with claim 14 wherein said electrode means further comprises two strips of conductive material disposed essentially perpendicular to a line drawn between said first surface hole of said first resonator and said first surface hole of said second resonator, said two conductive strips having a first end and a second end, a gap between said first end of each said conductive strip, and said second end of each said conductive strip connected to said conductive material of said side surface.

16. A radio utilizing an antenna to transmit radio frequency signals, comprising:

a transmitter; and

a filter disposed between said transmitter and the antenna, said filter comprising;

a volume of dielectric material having first, second, and side surfaces, said second and side surfaces being substantially covered with a conductive material;

a plurality of holes extending through said dielectric material from said first surface to said second surface, the surface of at least two said holes being substantially covered with a conductive material which is electrically common at said second surface, thereby forming at least two resonators; and

electrode means disposed on said first surface, connected to said conductive material of said side surface, and extending partially between a first surface hole of a first resonator of said at least two resonators and a first surface hole of a second resonator of said at least two resonators, whereby a coupling between said first resonator and said second resonator may be limited.

17. A radio in accordance with claim 16 wherein said electrode means further comprises two strips of conductive material disposed essentially perpendicular to a line drawn between said first surface hole of said first resonator and said first surface hole of said second resonator, said two conductive strips having a first end and a second end, a gap between said first end of each conductive strip, and said second end of each said conductive strip connected to said conductive material of said side surface.

18. A duplex radio transceiver capable of employing a single antenna for both receive and transmit functions comprising:

a transmitter;

a receiver; and

a duplexer filter disposed between said transmitter and the antenna, and between said receiver and the antenna, said duplexer filter comprising;

at least two volumes of dielectric material, each volume of dielectric material having first, second, and side surfaces, said second and side surfaces of each volume of dielectric material being substantially covered with a conductive material;

a plurality of holes extending through each said volume of dielectric material from said first surface to said second surface, the surface of at least two of said holes through each of said volume of dielectric material being substantially covered with a conductive material which is electrically common at said second surface of each respective volume of dielectric material, thereby forming at least two resonators in each said volume of dielectric material; and

electrode means disposed on said first surface of at least one of said volumes of dielectric material, connected to said conductive material of said side surface, and extending partially between a first surface hole of a first resonator of said at least two resonators and a first surface hole of a second resonator of said at least two resonators, whereby a coupling between said first resonator and said second resonator may be limited; and

coupling means for coupling a first volume of dielectric material having said at least two resonators therein tuned to a passband of transmitter frequencies and a second volume of dielectric material having said at least two resonators therein tuned to a passband of receiver frequencies to a single node at the single antenna, whereby said passband of transmitter frequencies is passed by said first volume of dielectric material and said passband of receiver frequencies is rejected by said first volume of dielectric material and said passband of receiver frequencies is passed by said second volume of dielectric material and said passband of transmitter frequencies is rejected by said second volume of dielectric material.

19. A duplex radio transceiver in accordance with claim 18 wherein said electrode means further comprises two strips of conductive material disposed essentially perpendicular to a line drawn between said first surface hole of said first resonator and said first surface hole of said second resonator, said two conductive strips having a first end and a second end, a gap between said first end of each said conductive strip, and said second end of each said conductive strip connected to said conductive material of said side surface.

20. A duplex radio transceiver in accordance with claim 18 further comprising a third resonator in at least one of said volumes of dielectric material adjusted to provide a transmission zero outside of said passband of said at least one of said volumes of dielectric material.

21. A duplex radio transceiver in accordance with claim 18 wherein said coupling means further comprises at least one transmission line.